java中SPI服务提供者的接口使用总结

public interface SpiService {
    /**
     * 呼叫方式
     */
    void call();
}

package com.lmy.config;

import com.lmy.service.SpiService;

import java.util.ArrayList;
import java.util.List;
import java.util.ServiceLoader;

/**
 * @author : lmy
 * @date : 2024/9/14 上午 11:35
 * 加载具体的服务实现
 */
public class SpiServiceLoader {
    private static volatile SpiServiceLoader LOADER;

    private final SpiService spiService;

    private final List<SpiService> spiServiceList;

    /**
     * 加载服务
     * */
    private SpiServiceLoader() {
        ServiceLoader<SpiService> loader = ServiceLoader.load(SpiService.class);
        List<SpiService> list = new ArrayList<>();
        for (SpiService spiService : loader) {
            list.add(spiService);
        }
        spiServiceList = list;
        if (!list.isEmpty()) {
            // 取第一个
            spiService = list.get(0);
        } else {
            spiService = null;
        }
    }

    /**
     * SpiServiceLoader 单例加载
     * */
    public static SpiServiceLoader getLOADER() {
        if (LOADER == null) {
            synchronized (SpiServiceLoader.class) {
                if (LOADER == null) {
                    LOADER = new SpiServiceLoader();
                }
            }
        }
        return LOADER;
    }


    public void call(){
        if(spiServiceList.isEmpty()){
            System.out.println("SpiService服务未加载！");
        }else {
            SpiService spiService = spiServiceList.get(0);
            spiService.call();
        }
    }

}

package com.lmy.service.impl;

import com.lmy.service.SpiService;

/**
 * @author : lmy
 * @date : 2024/9/14 上午 10:58
 * 默认实现
 */
public class SpiServiceImpl implements SpiService {
    @Override
    public void call() {
        System.out.println("默认手机呼叫");
    }
}

com.lmy.service.impl.SpiServiceImpl

<dependency>
    <groupId>com.lmy</groupId>
    <artifactId>SPI-interface</artifactId>
    <version>1.0-SNAPSHOT</version>
</dependency>

package com.lmy.Spi;

import com.lmy.config.SpiServiceLoader;
import org.junit.Test;

/**
 * @author : lmy
 * @date : 2024/9/14 上午 11:48
 */
public class SpiTest {

    @Test
    public void spiTest () {
        SpiServiceLoader loader = SpiServiceLoader.getLOADER();
        loader.call();
    }
}

package com.lmy.Spi.service;

import com.lmy.service.SpiService;

/**
 * @author : lmy
 * @date : 2024/9/14 下午 2:09
 */
public class SpiServiceNewImpl implements SpiService {
    @Override
    public void call() {
        System.out.println("卫星直呼");
    }
}

com.lmy.Spi.service.SpiServiceNewImpl